1. Field of the Invention
The present invention relates to industrial nickel plating mainly used for repair of aircraft components and so on, and particularly relates to industrial nickel plating used in the field where it is required to perform plating on a complicated-shaped object to be plated with a uniform and heavy thickness.
2. Description of the Prior Art
In overhauling aircraft components such as landing gear components made of ultra high strength steel, when occurrence of corrosion or cracks in a surface portion of the components is found, the portion is mechanically removed out and repaired by industrial nickel plating. In the conventional technique, repair plating has been carried out mainly by use of a nickel sulfamate bath with a soluble nickel anode. Most of aircraft components are, however, complicated in shape, and it is required to achieve the plating on the selected portion. Therefore, a suitable conforming anode is indispensable. In this case, however, there has been a problem that the fabrication of the conforming anode is difficult and expensive, since the mechanical fabrication of nickel is difficult and expensive. Moreover, since the nickel sulfamate bath tends to form pitting (pin holes) in the plated surface, the use of an organic anti-pitting agent is indispensable. However, there has been a problem that if the organic anti-pitting agent decomposes and changes in its properties during plating operation, the physical properties of the plating deposit are deteriorated and therefore it is required to intermittently carry out the activated charcoal treatment and filtration to thereby eliminate organic impurities so that the maintenance control of the bath is expensive and not easy. There has been a further problem in that the conventional sulfamate nickel plating causes hydrogen embrittlement in ultra high strength steel, which has an ultimate tensile strength of 260 kilo pound per square inch (KSi), and in order to eliminate the absorbed hydrogen, it is required to carry out a hydrogen relief baking treatment for a minimum of 23 hours so that the process takes excessive time and becomes expensive.